s390/mm: Simplify noexec page protection handling

By default page protection definitions like PAGE_RX have the _PAGE_NOEXEC
bit set. For older machines without the instruction execution protection
facility this bit is not allowed to be used in page table entries, and
therefore must be removed.

This is done at a couple of page table walkers, but also at some but not
all page table modification functions like ptep_modify_prot_commit(). Avoid
all of this and change the page, segment and region3 protection definitions
so that the noexec bit is masked out automatically if the instruction
execution-protection facility is not available. This is similar to what
also various other architectures do which had to solve the same problem.

Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

1 files changed, 61 insertions, 32 deletions

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 889974fc9810..a3b51056a177 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -124,6 +124,8 @@ static inline int is_module_addr(void *addr)
 #define KASLR_LEN	0UL
 #endif
 
+void setup_protection_map(void);
+
 /*
  * A 64 bit pagetable entry of S390 has following format:
  * |			 PFRA			      |0IPC|  OS  |
@@ -442,76 +444,107 @@ static inline int is_module_addr(void *addr)
 /*
  * Page protection definitions.
  */
-#define PAGE_NONE	__pgprot(_PAGE_PRESENT | _PAGE_INVALID | _PAGE_PROTECT)
-#define PAGE_RO		__pgprot(_PAGE_PRESENT | _PAGE_READ | \
+#define __PAGE_NONE		(_PAGE_PRESENT | _PAGE_INVALID | _PAGE_PROTECT)
+#define __PAGE_RO		(_PAGE_PRESENT | _PAGE_READ | \
 				 _PAGE_NOEXEC  | _PAGE_INVALID | _PAGE_PROTECT)
-#define PAGE_RX		__pgprot(_PAGE_PRESENT | _PAGE_READ | \
+#define __PAGE_RX		(_PAGE_PRESENT | _PAGE_READ | \
 				 _PAGE_INVALID | _PAGE_PROTECT)
-#define PAGE_RW		__pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
+#define __PAGE_RW		(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
 				 _PAGE_NOEXEC  | _PAGE_INVALID | _PAGE_PROTECT)
-#define PAGE_RWX	__pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
+#define __PAGE_RWX		(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
 				 _PAGE_INVALID | _PAGE_PROTECT)
-
-#define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
+#define __PAGE_SHARED		(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
 				 _PAGE_YOUNG | _PAGE_DIRTY | _PAGE_NOEXEC)
-#define PAGE_KERNEL	__pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
+#define __PAGE_KERNEL		(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
 				 _PAGE_YOUNG | _PAGE_DIRTY | _PAGE_NOEXEC)
-#define PAGE_KERNEL_RO	__pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_YOUNG | \
+#define __PAGE_KERNEL_RO	(_PAGE_PRESENT | _PAGE_READ | _PAGE_YOUNG | \
 				 _PAGE_PROTECT | _PAGE_NOEXEC)
 
+extern unsigned long page_noexec_mask;
+
+#define __pgprot_page_mask(x)	__pgprot((x) & page_noexec_mask)
+
+#define PAGE_NONE		__pgprot_page_mask(__PAGE_NONE)
+#define PAGE_RO			__pgprot_page_mask(__PAGE_RO)
+#define PAGE_RX			__pgprot_page_mask(__PAGE_RX)
+#define PAGE_RW			__pgprot_page_mask(__PAGE_RW)
+#define PAGE_RWX		__pgprot_page_mask(__PAGE_RWX)
+#define PAGE_SHARED		__pgprot_page_mask(__PAGE_SHARED)
+#define PAGE_KERNEL		__pgprot_page_mask(__PAGE_KERNEL)
+#define PAGE_KERNEL_RO		__pgprot_page_mask(__PAGE_KERNEL_RO)
+
 /*
  * Segment entry (large page) protection definitions.
  */
-#define SEGMENT_NONE	__pgprot(_SEGMENT_ENTRY_PRESENT | \
+#define __SEGMENT_NONE		(_SEGMENT_ENTRY_PRESENT | \
 				 _SEGMENT_ENTRY_INVALID | \
 				 _SEGMENT_ENTRY_PROTECT)
-#define SEGMENT_RO	__pgprot(_SEGMENT_ENTRY_PRESENT | \
+#define __SEGMENT_RO		(_SEGMENT_ENTRY_PRESENT | \
 				 _SEGMENT_ENTRY_PROTECT | \
 				 _SEGMENT_ENTRY_READ | \
 				 _SEGMENT_ENTRY_NOEXEC)
-#define SEGMENT_RX	__pgprot(_SEGMENT_ENTRY_PRESENT | \
+#define __SEGMENT_RX		(_SEGMENT_ENTRY_PRESENT | \
 				 _SEGMENT_ENTRY_PROTECT | \
 				 _SEGMENT_ENTRY_READ)
-#define SEGMENT_RW	__pgprot(_SEGMENT_ENTRY_PRESENT | \
+#define __SEGMENT_RW		(_SEGMENT_ENTRY_PRESENT | \
 				 _SEGMENT_ENTRY_READ | \
 				 _SEGMENT_ENTRY_WRITE | \
 				 _SEGMENT_ENTRY_NOEXEC)
-#define SEGMENT_RWX	__pgprot(_SEGMENT_ENTRY_PRESENT | \
+#define __SEGMENT_RWX		(_SEGMENT_ENTRY_PRESENT | \
 				 _SEGMENT_ENTRY_READ | \
 				 _SEGMENT_ENTRY_WRITE)
-#define SEGMENT_KERNEL	__pgprot(_SEGMENT_ENTRY |	\
+#define __SEGMENT_KERNEL	(_SEGMENT_ENTRY |	\
 				 _SEGMENT_ENTRY_LARGE |	\
 				 _SEGMENT_ENTRY_READ |	\
 				 _SEGMENT_ENTRY_WRITE | \
 				 _SEGMENT_ENTRY_YOUNG | \
 				 _SEGMENT_ENTRY_DIRTY | \
 				 _SEGMENT_ENTRY_NOEXEC)
-#define SEGMENT_KERNEL_RO __pgprot(_SEGMENT_ENTRY |	\
+#define __SEGMENT_KERNEL_RO	(_SEGMENT_ENTRY |	\
 				 _SEGMENT_ENTRY_LARGE |	\
 				 _SEGMENT_ENTRY_READ |	\
 				 _SEGMENT_ENTRY_YOUNG |	\
 				 _SEGMENT_ENTRY_PROTECT | \
 				 _SEGMENT_ENTRY_NOEXEC)
 
+extern unsigned long segment_noexec_mask;
+
+#define __pgprot_segment_mask(x) __pgprot((x) & segment_noexec_mask)
+
+#define SEGMENT_NONE		__pgprot_segment_mask(__SEGMENT_NONE)
+#define SEGMENT_RO		__pgprot_segment_mask(__SEGMENT_RO)
+#define SEGMENT_RX		__pgprot_segment_mask(__SEGMENT_RX)
+#define SEGMENT_RW		__pgprot_segment_mask(__SEGMENT_RW)
+#define SEGMENT_RWX		__pgprot_segment_mask(__SEGMENT_RWX)
+#define SEGMENT_KERNEL		__pgprot_segment_mask(__SEGMENT_KERNEL)
+#define SEGMENT_KERNEL_RO	__pgprot_segment_mask(__SEGMENT_KERNEL_RO)
+
 /*
  * Region3 entry (large page) protection definitions.
  */
 
-#define REGION3_KERNEL	__pgprot(_REGION_ENTRY_TYPE_R3 | \
+#define __REGION3_KERNEL	(_REGION_ENTRY_TYPE_R3 | \
 				 _REGION3_ENTRY_PRESENT | \
-				 _REGION3_ENTRY_LARGE |	 \
-				 _REGION3_ENTRY_READ |	 \
-				 _REGION3_ENTRY_WRITE |	 \
-				 _REGION3_ENTRY_YOUNG |	 \
+				 _REGION3_ENTRY_LARGE | \
+				 _REGION3_ENTRY_READ | \
+				 _REGION3_ENTRY_WRITE | \
+				 _REGION3_ENTRY_YOUNG | \
 				 _REGION3_ENTRY_DIRTY | \
 				 _REGION_ENTRY_NOEXEC)
-#define REGION3_KERNEL_RO __pgprot(_REGION_ENTRY_TYPE_R3 | \
-				   _REGION3_ENTRY_PRESENT | \
-				   _REGION3_ENTRY_LARGE |  \
-				   _REGION3_ENTRY_READ |   \
-				   _REGION3_ENTRY_YOUNG |  \
-				   _REGION_ENTRY_PROTECT | \
-				   _REGION_ENTRY_NOEXEC)
+#define __REGION3_KERNEL_RO	(_REGION_ENTRY_TYPE_R3 | \
+				 _REGION3_ENTRY_PRESENT | \
+				 _REGION3_ENTRY_LARGE | \
+				 _REGION3_ENTRY_READ | \
+				 _REGION3_ENTRY_YOUNG | \
+				 _REGION_ENTRY_PROTECT | \
+				 _REGION_ENTRY_NOEXEC)
+
+extern unsigned long region_noexec_mask;
+
+#define __pgprot_region_mask(x)	__pgprot((x) & region_noexec_mask)
+
+#define REGION3_KERNEL		__pgprot_region_mask(__REGION3_KERNEL)
+#define REGION3_KERNEL_RO	__pgprot_region_mask(__REGION3_KERNEL_RO)
 
 static inline bool mm_p4d_folded(struct mm_struct *mm)
 {
@@ -1412,8 +1445,6 @@ static inline pte_t mk_pte_phys(unsigned long physpage, pgprot_t pgprot)
 	pte_t __pte;
 
 	__pte = __pte(physpage | pgprot_val(pgprot));
-	if (!MACHINE_HAS_NX)
-		__pte = clear_pte_bit(__pte, __pgprot(_PAGE_NOEXEC));
 	return pte_mkyoung(__pte);
 }
 
@@ -1781,8 +1812,6 @@ static inline int pmdp_clear_flush_young(struct vm_area_struct *vma,
 static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
 			      pmd_t *pmdp, pmd_t entry)
 {
-	if (!MACHINE_HAS_NX)
-		entry = clear_pmd_bit(entry, __pgprot(_SEGMENT_ENTRY_NOEXEC));
 	set_pmd(pmdp, entry);
 }